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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Monday, January 17, 2022

SPC Jan 17, 2022 0830 UTC Day 3 Severe Thunderstorm Outlook

SPC 0830Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0200 AM CST Mon Jan 17 2022 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE UPPER TEXAS COAST INTO THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe thunderstorms may occur Wednesday from parts of the upper Texas Coast into the lower Mississippi Valley. ...Upper Texas Coast into the Lower Mississippi Valley... A low-amplitude, southern-stream shortwave trough should eject quickly eastward from the southern High Plains to the lower MS Valley on Wednesday. At the surface, a weak low initially in the vicinity of the ArkLaTex is likewise forecast to develop towards the Mid-South through the day, while a strong cold front moves southward across the southern Plains and lower MS Valley in its wake. The return of a partially modified Gulf airmass should continue ahead of the cold front across much of the TX Coastal Plain and into parts of the lower MS Valley. Due to a prior frontal passage shunting rich low-level moisture well south into the Gulf of Mexico, this moisture return is forecast to remain fairly muted, with generally mid 50s to low 60s surface dewpoints expected over land. With only modest diurnal heating, weak instability capable of supporting surface-based convection should develop in a fairly narrow corridor ahead of the cold front, extending from the upper TX Coast northeastward into portions of LA/MS. Fairly long, straight hodographs and strengthening winds with height through mid levels shown in various NAM forecast soundings across this region suggest around 40-50 kt of deep-layer shear should be present. This shear will likely support thunderstorm organization, and some supercell potential with initial development Wednesday afternoon. Isolated large hail may occur with this activity, although mid-level lapse rates are not expected to be overly steep. With time, convection should grow upscale along/ahead of the front as both move south-southeastward. Damaging winds should become a greater concern as this mode transition occurs. A tornado or two also appears possible, as a 30-40 kt southwesterly low-level jet should linger over the warm sector through much of the day, enhancing low-level shear. Eventually, the convection should outpace the modest low-level moisture return, and a weakening trend should occur Wednesday evening/night across southern LA/MS into AL. ..Gleason.. 01/17/2022 Read more CHECK UPDATE ZOOM GRAPHIC